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Journal article
Reconstructing extreme climatic and geochemical conditions during the largest natural mangrove dieback on record
Biogeosciences, Vol.17(18), pp.4707-4726
28/09/2020
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Abstract
A massive mangrove dieback event occurred in 2015–2016 along ∼1000 km of pristine coastline in the Gulf of Carpentaria, Australia. Here, we use sediment and wood chronologies to gain insights into geochemical and climatic changes related to this dieback. The unique combination of low rainfall and low sea level observed during the dieback event had been unprecedented in the preceding 3 decades. A combination of iron (Fe) chronologies in wood and sediment, wood density and estimates of mangrove water use efficiency all imply lower water availability within the dead mangrove forest. Wood and sediment chronologies suggest a rapid, large mobilization of sedimentary Fe, which is consistent with redox transitions promoted by changes in soil moisture content. Elemental analysis of wood cross sections revealed a 30- to 90-fold increase in Fe concentrations in dead mangroves just prior to their mortality. Mangrove wood uptake of Fe during the dieback is consistent with large apparent losses of Fe from sediments, which potentially caused an outwelling of Fe to the ocean. Although Fe toxicity may also have played a role in the dieback, this possibility requires further study. We suggest that differences in wood and sedimentary Fe between living and dead forest areas reflect sediment redox transitions that are, in turn, associated with regional variability in groundwater flows. Overall, our observations provide multiple lines of evidence that the forest dieback was driven by low water availability coinciding with a strong El Niño–Southern Oscillation (ENSO) event and was associated with climate change.
Details
- Title
- Reconstructing extreme climatic and geochemical conditions during the largest natural mangrove dieback on record
- Creators
- James Z Sippo (Corresponding Author) - Southern Cross UniversityIsaac R Santos - Southern Cross UniversityChristian J Sanders - Southern Cross UniversityPatricia Gadd - Australian Nuclear Science and Technology OrganisationQuan Hua - Australian Nuclear Science and Technology OrganisationCatherine E Lovelock - University of QueenslandNadia S Santini - Consejo Nacional de Ciencia y TecnologíaScott G Johnston - Southern Cross UniversityYota Harada - Griffith UniversityGloria Reithmeir - Southern Cross UniversityDamien Maher - Southern Cross University
- Publication Details
- Biogeosciences, Vol.17(18), pp.4707-4726
- Publisher
- Copernicus GmbH
- Grants
- Beyond burial: redefining the blue carbon paradigm, DP180101285, Australian Research CouncilIncrease of soil carbon burial in mangrove wetlands, DP150103286, Australian Research Council
- Identifiers
- 991012885400302368
- Copyright
- © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License.
- Academic Unit
- Faculty of Science and Engineering; School of Environment, Science and Engineering; National Marine Science Centre; Southern Cross GeoScience; Science; National Centre for Flood Research
- Language
- English
- Resource Type
- Journal article